'm' is the gradient (or slope). We measure the difference between the two x values and two y values to see how each of them changed respectively. We know m = rise/run so we can put in our slope (7) and points to find t.
Given that the ball has a thickness of 1 cm and the radius at the outside is 5 cm, thus the radius from inside is 5 - 1 = 4cm.
The <span>approximate volume of rubber used to make the ball is given by the volume of the ball at the outside surface minus the volume of the ball at the inside surface.
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